Ampex is a company that had a strong start doing it's own R&D, and developing some really great digital technologies in the 40's and 50's, only to struggle and almost fall off the Stock exchange. Recently, however, it made an incredible comeback as it litigated it's way back to the top. It held some useful, and some would say, obvious patents used today in digital media everywhere. Is this the right way to do business? While it is perfectly legal to enforce ones patents, there probably ought to be a statute of limitations on enforcing them late in the game, although the patent itself may not have expired.
The Profits in the Attic - How an old technology has turned Ampex into America's hottest stock.